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From: Chandan Babu R <chandanrlinux@gmail.com>
To: linux-xfs@vger.kernel.org
Cc: Chandan Babu R <chandanrlinux@gmail.com>,
	darrick.wong@oracle.com, david@fromorbit.com
Subject: [PATCH V6 08/11] xfs: Check for extent overflow when remapping an extent
Date: Mon, 12 Oct 2020 14:59:35 +0530	[thread overview]
Message-ID: <20201012092938.50946-9-chandanrlinux@gmail.com> (raw)
In-Reply-To: <20201012092938.50946-1-chandanrlinux@gmail.com>

Remapping an extent involves unmapping the existing extent and mapping
in the new extent. When unmapping, an extent containing the entire unmap
range can be split into two extents,
i.e. | Old extent | hole | Old extent |
Hence extent count increases by 1.

Mapping in the new extent into the destination file can increase the
extent count by 1.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_inode_fork.h | 15 +++++++++++++++
 fs/xfs/xfs_reflink.c           |  5 +++++
 2 files changed, 20 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index b99e67e7b59b..ded3c1b56c94 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -87,6 +87,21 @@ struct xfs_ifork {
  */
 #define XFS_IEXT_REFLINK_END_COW_CNT	(2)
 
+/*
+ * Remapping an extent involves unmapping the existing extent and mapping in the
+ * new extent.
+ *
+ * When unmapping, an extent containing the entire unmap range can be split into
+ * two extents,
+ * i.e. | Old extent | hole | Old extent |
+ * Hence extent count increases by 1.
+ *
+ * Mapping in the new extent into the destination file can increase the extent
+ * count by 1.
+ */
+#define XFS_IEXT_REFLINK_REMAP_CNT(smap_real, dmap_written) \
+	(((smap_real) ? 1 : 0) + ((dmap_written) ? 1 : 0))
+
 /*
  * Fork handling.
  */
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 4f0198f636ad..c9f9ff68b5bb 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1099,6 +1099,11 @@ xfs_reflink_remap_extent(
 			goto out_cancel;
 	}
 
+	error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+			XFS_IEXT_REFLINK_REMAP_CNT(smap_real, dmap_written));
+	if (error)
+		goto out_cancel;
+
 	if (smap_real) {
 		/*
 		 * If the extent we're unmapping is backed by storage (written
-- 
2.28.0


  parent reply	other threads:[~2020-10-12  9:30 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-12  9:29 [PATCH V6 00/11] Bail out if transaction can cause extent count to overflow Chandan Babu R
2020-10-12  9:29 ` [PATCH V6 01/11] xfs: Add helper for checking per-inode extent count overflow Chandan Babu R
2020-10-15  8:34   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 02/11] xfs: Check for extent overflow when trivally adding a new extent Chandan Babu R
2020-10-15  8:34   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 03/11] xfs: Check for extent overflow when punching a hole Chandan Babu R
2020-10-15  8:35   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 04/11] xfs: Check for extent overflow when adding/removing xattrs Chandan Babu R
2020-10-15  8:36   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 05/11] xfs: Check for extent overflow when adding/removing dir entries Chandan Babu R
2020-10-15  8:36   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 06/11] xfs: Check for extent overflow when writing to unwritten extent Chandan Babu R
2020-10-15  8:36   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 07/11] xfs: Check for extent overflow when moving extent from cow to data fork Chandan Babu R
2020-10-15  8:37   ` Christoph Hellwig
2020-10-12  9:29 ` Chandan Babu R [this message]
2020-10-15  8:39   ` [PATCH V6 08/11] xfs: Check for extent overflow when remapping an extent Christoph Hellwig
2020-10-15 10:01     ` Chandan Babu R
2020-10-15 18:45       ` Darrick J. Wong
2020-10-16  4:27         ` Chandan Babu R
2020-10-16  7:04       ` Christoph Hellwig
2020-10-16 11:28         ` Chandan Babu R
2020-10-16 15:29           ` Darrick J. Wong
2020-10-17  2:55             ` Chandan Babu R
2020-10-12  9:29 ` [PATCH V6 09/11] xfs: Check for extent overflow when swapping extents Chandan Babu R
2020-10-12  9:29 ` [PATCH V6 10/11] xfs: Introduce error injection to reduce maximum inode fork extent count Chandan Babu R
2020-10-15  8:40   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 11/11] xfs: Introduce error injection to allocate only minlen size extents for files Chandan Babu R
2020-10-15  8:41   ` Christoph Hellwig
2020-10-15 10:02     ` Chandan Babu R
2020-10-15 18:41       ` Darrick J. Wong
2020-10-16 11:31         ` Chandan Babu R

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